Crystallographic Features of Copper Column Growth by Reversible Pulse Current Electrodeposition

Interconnection with single crystal could be attractive for more reliable, predictable and multifunctional electronics assembly at micro-to nano-scale, if each crystal joint has the same crystal structure and orientation. To achieve single crystal copper column growth, electrodeposition has been carried out with the assistance of reversible pulse plating techniques. Initial experiments to understand how plating process will influence the crystal growth provided a guidance for electrodeposition of single crystal copper columns. It has been found that reversible pulse current in large degree changed the morphology of electrodeposited copper compared to the direct current electrodeposition. Pulse parameter such as peak current density and frequency also affected the crystal growth and morphology of copper column formation. It has appeared that achieving single crystal growth by pulse plating alone is found to be less successful. Therefore, the challenges still exist to achieve single crystal copper column formation by electrodeposition. The possible future approaches may consider the related techniques including substrate treatment prior to deposition and ultrasonic agitation during deposition would be beneficial to eliminate the sites of nucleation.